IN August 1938, 17-year-old Georg Klaar and his parents fled their home in Vienna. The anti-Semitic rampages unleashed in Austria in the wake of the Austro-German Anschluss made those in Germany seem restrained by comparison and convinced many Austrian Jews, like the Klaars, of the grave dangers of staying where they were. The Klaars found a refuge in Ireland, but unfortunately, the parents returned to France, where they were eventually tracked down and deported to their deaths in the gas chambers of Auschwitz.

The same month the Klaars left Austria, a young American Jewish woman, Lucy Schildkret (a graduate of Hunter College, who later became known as a historian under her married name, Dawidowicz), left her native New York. She went, for a year of study, to the Yiddish Scientific Institute (YIVO) in the ancient Lithuanian city of Vilna, long a center of Jewish life and culture and, at that time, incorporated into greater Poland. Although she did not realize it at the time, Dawidowicz was visiting a world on the eve of its destruction.

George Clare's family had lived in Austria for generations. His great-grandfather Hermann Klaar, a physician who joined the Austrian army medical corps in 1849, was the first in the family to be ``completely assimilated ... believing himself wholly Austrian, no different from other Austrians, except perhaps for the relatively unimportant fact of practicing a minority religion.''

Lucy Dawidowicz's parents had little interest in religion, nor were they attracted by Zionism. Yet, unlike many other Westernized Jews, they did not wish to become ``assimilated'' (a term Dawidowicz distinguishes from the less drastic goal of becoming ``acculturated''). Each day, after attending New York City public schools, Dawidowicz went to classes in Yiddish language, literature, culture, and history.

She knew of Vilna's reputation as ``the Jerusalem of Lithuania.'' The vibrant cultural life she discovered there, however, was not altogether a sign of vitality: It was also a signal of distress, for it testified not only to a people's will to preserve their heritage, but also to the extent to which they were excluded from the Polish society around them.

As a historian, Dawidowicz has written elsewhere of the large-scale events of ``The War Against the Jews'' - the title of her classic book. In her memoir, ``From This Place and Time,'' she focuses instead on her own experiences. She writes simply yet powerfully of her own emotions as scholar and witness: her year in Vilna; the tension-filled war years back in America, reading worse and worse news of what was happening to the Jews of Europe; and her return to Europe after the war, meeting with some of the survivors and rescuing the remains of the YIVO library.

Ever the scrupulous historian, not trusting to her own memory, Dawidowicz decided to write a memoir only after she discovered that some 100 letters she had written home had been saved by their recipients. She provides us with a rich gallery of portraits of the people she came to know that year in Vilna.

Harassed as they were, the Jews of Vilna, who warned her to leave Europe before war broke out, envisioned hunger, violence, and deprivation, but not the destruction of the world as they knew it. Her book captures the dedication of the YIVO scholars, the hospitality and warmth of the family she stayed with, and the energy and hope of the students and literati who gathered at Velfkeh's, the local cafe.

Clare's memoir, ``Last Waltz in Vienna,'' (which appeared first in a German translation in 1980, then in English hardcover in 1981) ventures further beyond personal experience, seamlessly combining 100 years of family history and cultural history.

There are vivid portraits of family members, plus a wry account of Clare's own youth nurtured on stories of German heroism from a popular boys' magazine, Der Gute Kamerad. Clare discusses such Viennese figures as satirist Karl Kraus, playwright Arthur Schnitzler, and Zionist Theodor Herzl.

Most Viennese Jews, Clare believes, suffered from a ``security complex'' rather than the classic ``persecution complex.'' (He quotes these contrasting phrases from Schnitzler.) Yet the Austria that seemed so secure a home had been seething for decades with nationalist cults, decadent self-loathing, and a fresh racist strain of the old-fashioned virulence of anti-Semitism.

Clare's writing conveys a fine sense of these ironies, and, as irony gives way to tragedy, the contrast between images of domesticity and the unimaginable fate of countless families becomes almost unbearable. The Klaars' last message, thrown from the train that took them to their deaths, was about saving their household furnishings for their son to inherit. (It was to no avail: The Nazis had already taken the furniture and pictures.)

Memoirs are primarily defined as ``history written from personal knowledge.'' The stamp of individual experience helps make real to those who were not there the large events in history that are so notoriously hard to grasp. Both these memoirs pay homage to those who were killed by speaking of them and in some sense for them. Both, in their different ways, do more than provide eyewitness testimony to events, do more than fill in the details of lost faces. Each captures the texture and flavor of a way of life that vanished more abruptly than even the most pessimistic could foresee.